Call dynamic class hook on generic classes (#16052) #400

Job	Run time
Test mypyc suite with 32-bit Python	10m 25s
Test suite with py38-ubuntu, mypyc-compiled	22m 20s
Test suite with py38-windows-64	46m 31s
Test suite with py39-ubuntu	28m 59s
Test suite with py310-ubuntu	31m 44s
Test suite with py311-ubuntu, mypyc-compiled	20m 22s
Test suite with py312-ubuntu, mypyc-compiled	23m 41s
mypyc runtime tests with py38-macos	7m 47s
mypyc runtime tests with py38-debug-build-ubuntu	7m 32s
Type check our own code (py38-ubuntu)	2m 7s
Type check our own code (py38-windows-64)	2m 50s
Formatting and code style with Black + ruff	41s
	3h 24m 59s

Provide feedback